1. Field of the Invention
The present invention relates to an ink jet ink composition, an ink-set and an ink jet treatment liquid which are used for an ink jet recording apparatus (e.g., a printer, a copier, a facsimile, or a word processor), and an ink jet recording method and an ink jet recording apparatus which use the ink jet ink composition, the ink-set and the ink jet treatment liquid.
2. Description of the Related Art
A so-called ink jet recording apparatus in which a liquid or a molten solid ink is ejected through a nozzle, slit, porous film or the like to record onto paper, cloth, film, or the like has various advantages such as being compact, inexpensive and quiet. Many kinds of these recording apparatuses including not only monochrome printers, but also color printers capable of recording full-color images, with which a good quality is obtained on plain paper such as report paper, copy paper, or the like, have been recently sold in the market, and thereby occupy a large share for the market of recording apparatus. Among these ink jet recording apparatuses, so-called piezo ink jet printers using piezoelectric elements, and so-called thermal ink jet recording apparatuses which use heat energy to form droplets and then print have various advantages such as high printing speed and high resolution.
The ink used in the ink jet recording apparatus mainly contains a solvent, a colorant and additives. The following characteristics are required for the ink jet recording ink: that the ink can provide uniform, blotting-free and fog-free images with high resolution and high density; that the ink causes no clogging at the tip of the nozzle due to dried ink and always exhibits good ejecting responsiveness and good ejecting stability; that the ink rapidly dries on paper; that the ink has good image fastness; and the ink has good long-term storage stability.
In addition, there is a need for an ink having characteristics such that it relieves or suppress a noticeable incidence of curling of a recording medium such as regular paper. Curl refers to a phenomenon in which a recording medium becomes rounded during or after printing.
The curled recording medium is quite inconvenient since the recording medium cannot be piled or spread out into a sheet. Curl of the sheet is particularly a problem when color graphic images having many solid printing portions are continuously printed at a high speed. Moreover, since curl makes it difficult to print on both faces, it is necessary to suppress and relieve curling of recording media for this reason as well.
It has been proposed to use 1,3-diols, 1,3,5-triols and amino-1,3-diols as anti-curl agents in the ink in order to suppress curling (see Japanese Patent Application Laid-Open (JP-A) No. 6-157955). Adding amide compounds in the ink as the anti-curl agent has been also proposed (see JP-A No. 9-176538). Adding hydroxyamide derivatives in the ink as the anti-curl agent has been further proposed (see JP-A No. 10-204348).
However, although these methods can suppress curling, a large quantity of the anti-curl agent must be added in he ink to suppress curling. Accordingly, the ink in which a large quantity of the anti-curl agent is added causes insufficient image quality, clogging of nozzles, lower apparatus reliability, and the like. Thus, these methods are not sufficient.
Some techniques for suppressing curl by treating a recording medium have been proposed. For example, a method in which a back-coat layer is provided at a surface opposite from an ink receiving layer of the recording medium (see JP-A No. 8-310111) has been proposed. Also, it has been proposed to use a regular paper type recording medium in which irreversible shrinkage factors of the paper in a machine direction (MD) and a cross direction (CD) when the relative humidity is changed are controlled (see JP-A No. 9-234946). A method for controlling the degree of curl size of a coating layer and a surface opposite from the coating layer has been further proposed (see JP-A No. 10-278413).
However, although some effects of improving curl is obtained with these conventional techniques, these are not sufficient. Since users are required to purchase recording media treated with the anti-curl agent, convenience for general users is compromised. Considering user convenience, an ink that is able to prevent curling when any recording media is used for printing is more convenient and more desired than the recording medium treated with the anti-curl agent.